Thirty Minutes Before the Dawn—Trinity Alan B

Submitted to ANS/NT (2021), LA-UR-21-21007

Thirty Minutes Before the Dawn—Trinity Alan B. Carr* Los Alamos National Laboratory Los Alamos, NM 87545 The Trinity test of July 16, 1945, marked the scientific apex of the Manhattan Project. Often recognized as the symbolic birth of the nuclear age, Trinity’s multifaceted legacy remains just as captivating and complex today as it did 75 years ago. This paper examines why the test was necessary from a technical standpoint, shows how Los Alamos scientists planned the event, and explores the physical and emotional aftermaths of Trinity. The author also uses rarely accessed original records to reconstruct the story of Trinity’s health hazards, as seen through the eyes of radiation technicians and medical doctors as events unfolded. Trinity was conducted as the Potsdam Conference began, weeks after the collapse of Nazi Germany. It was considered necessary to let President Harry S. Truman know whether the United States possessed a nuclear capability ahead of his negotiations with Joseph Stalin, the Soviet premier. The author examines the competing priorities that drove the timetable for the test: international politics, security, and safety. Three weeks after Trinity, a gun-assembled enriched-uranium bomb called Little Boy was used against the Japanese city of Hiroshima. Three days later, Fat Man, a weaponized version of the imploding Trinity device, was dropped on Nagasaki. The author briefly examines these strikes and what impact they may have had on the Japanese surrender. The paper concludes by examining the legacy of the Trinity test 75 years into the age it helped usher in. Keywords: Trinity, Los Alamos, Oppenheimer, fallout

I. One of the Great Events of History weapons developed during the war? When the work at Los Alamos began, the most promising path to success Seventy-five years ago, Los Alamos scientists secretly appeared to be constructing gun-type weapons because, conducted the world’s first nuclear weapons test. The from an engineering standpoint, gun assembly seemed story of this historic event is well known; it has been less complex and far more certain than proposed shared many times, by many people, over the decades. alternatives. In a gun-assembled nuclear weapon, a But this test, dubbed “Trinity” by Los Alamos Director J. subcritical mass of fissile material is fired at another Robert Oppenheimer, did not happen in a vacuum. As the subcritical fissile mass to produce a nuclear detonation. first day of the nuclear age dawned in New Mexico, The plutonium gun weapon was given the name Thin fighting continued throughout Japan’s disintegrating Man; Little Boy was its enriched uranium counterpart. empire in places such as Borneo, Burma, China, and the But in the spring of 1944, experiments performed by Philippines. In the coming weeks, Stalin’s armies would future Nobel laureate Emilio Segrè began to cast doubt on bring the war to the Japanese in Manchuria and Sakhalin. the viability of Thin Man: such a device might The large cities of Japan endured heavy bombing predetonate because of spontaneous fission in the isotope throughout this period, while kamikazes desperately tried 240Pu. That July, Segrè’s troubling results were to break the ever tightening Allied blockade. But when confirmed: Thin Man would detonate before it was fully Oppenheimer’s fearsome creation detonated in the New assembled.1 The demise of Thin Man is where the story Mexican desert, there was awe-inspiring silence in the of Trinity begins. immediate aftermath. Of course, it would not last: the fleeting serenity would be broken after several moments II. All Possible Priority by the passage of a violent shock wave. Soon, that same At an administrative board meeting on the morning of elemental force would break the morning in Japan, as July 20, 1944, held just hours after Hitler narrowly well, and, in doing so help break the Japanese escaped an assassination attempt in distant East Prussia, government’s will to continue the war. The course of Oppenheimer directed, “All possible priority should be history rarely changes dramatically in just an instant, but given to the implosion program. At the same time, that’s exactly what happened the morning of July 16, nothing essential to the 25 [code for 235U] gun should be 1945. left undone.”2 In an imploding weapon, a sphere of fissile But why perform a test in the first place? And, more material is surrounded by high explosives (HE); when the fundamentally, why were two entirely different types of HE detonates, the blast wave compresses the fissile core

* E-mail: [email protected]

Submitted to ANS/NT (2021), LA-UR-21-21007 to supercriticality, thus producing a nuclear detonation overcome many daunting technical challenges quickly. In (see Brown and Borovina3 and Moore,4 this issue). The late 1944 and into the spring of 1945, as plutonium and implosion concept was more complex than a gun, but highly enriched uranium were becoming available in such a design would overcome the predetonation problem greater amounts,6 hundreds of experiments were and require less fissile material. Meanwhile, progress was performed to try to better understand the hydrodynamics being made to determine the critical masses and hence the of implosion. Scientists struggled to develop a reliable amounts of special nuclear material needed (see detonator and a circuit for firing dozens of them Chadwick,5 Hutchinson et al.,6 and Kimpland et al.,7 this simultaneously. The bomb would rely on thousands of issue). Just two weeks later, Oppenheimer reorganized pounds of HE to drive the implosion; the large blocks of the Laboratory to make the implosion concept a reality. HE, which fit together like a spherical, three-dimensional Two new divisions were created to develop the “gadget,” jigsaw puzzle, would need to be precisely shaped and as the implosion bomb would become known. The first, skillfully cast. As work progressed, confidence increased. the Weapons Physics, or Gadget, Division (G) was led by See Martz et al.15 and Crockett and Freibert,16 this issue, Robert F. Bacher, formerly head of the Physics Division. on the remarkable properties of plutonium that needed to George Kistiakowsky, a Ukrainian-born veteran of the be understood. The design innovations in the Theoretical Russian Civil War, would lead the Explosives Division Division that led to the “Christy gadget,” a spherical solid (X). Both divisions were formally established on August plutonium core, are described in this issue by Chadwick 14, 1944: the Japanese emperor would announce the and Chadwick.17 termination of hostilities exactly one year later, thanks in At no point, however, were most scientists confident part to the work of these new organizations.8 enough to put an implosion bomb into combat without a The Theoretical Division under Hans Bethe’s full-scale test first. Kenneth Bainbridge, the Harvard leadership played a central role in advancing the basic physicist whom Oppenheimer would soon entrust to serve science studied during the Manhattan Project. These as test director, offers two reasons. First, “A test of the include shock hydrodynamics (Morgan and Archer,9 this atomic bomb was considered essential by the Director and issue) and neutronics (Sood et al.,10 this issue). Bethe and most of the group and division leaders of the Laboratory Feynman, both future Nobel laureates, developed an because of the enormous step from the differential and important equation for predicting the expected nuclear integral experiments, and theory, to a practical gadget.” fission efficiency, as described by Lestone.11 Computing And, “No one was content that the first trial of a Fat Man using both “human computers” and IBM punched-card (F. M.) gadget should be over enemy territory, where, if machines enabled these Theoretical Division efforts, too, the gadget failed, the surprise factor would be lost and the as described by Lewis12 and Archer.13 enemy might be presented with a large amount of active It is well known that Little Boy entered combat without material in recoverable form.”18 When the weapon a full-scale test, but there is more to the story. Every entered combat, there could be absolutely no doubt it component of the gun weapon was rigorously tested at would work. The implosion bomb’s complex and Los Alamos. For instance, nuclear criticality experiments revolutionary design demanded a test. confirmed that the Little Boy design was reliable: the odds of a malfunction were astronomically small. So why III. Planning the Unprecedented even pursue an imploding bomb if the Laboratory already Over the years, many have conjectured where the name had a very promising design? Though Little Boy was Trinity came from. In fact, it was Oppenheimer who reliable, the design suffered from a significant flaw—it named Trinity. In October 1962, as General Leslie R. was terribly inefficient. The challenges of enriching Groves, commander of the Manhattan Engineer District, uranium meant that there was not enough material to was preparing his memoir, he wrote to his former rapidly replicate combat units. This flaw was noted in a subordinate to inquire about the test’s legendary name. A Laboratory memo by future Nobel laureate Norman few days later, in the midst of the Cuban Missile Crisis, Ramsey: “The frequency of availability of active units Oppenheimer responded, “I did suggest it,” but will be sufficiently low for some time that their military continued, “Why I chose the name is not clear, but I know effectiveness will probably be relatively small.”14 In what thoughts were in my mind.” The former Los Alamos short, Little Boy was little more than a one-off gimmick, director had been reading the poetry of John Donne at the not an easily reproduced weapon. In order to threaten the time. In the letter, he quotes a line from one of Donne’s enemy with a truly novel capability, it was necessary to Holy Sonnets, “Batter my heart, three person’d God;—,” have more weapons available for combat. The only way concluding, “Beyond this, I have no clues whatever.”19 to do that was to perfect an imploding plutonium bomb. This clear reference to Christianity’s holy trinity most The possibility of an efficient implosion weapon was likely inspired Oppenheimer’s celestial moniker. alluring, but the Los Alamos staff would have to

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But where would Trinity take place? Months before visible over a wide region. To minimize the number of Oppenheimer reorganized his staff to focus on implosion, potential witnesses, the detonation was scheduled for 4:00 just as gloom started to envelop the Thin Man program, a.m., an hour when most in the surrounding area would the search for a site began.20 In mid-June, as efforts remain sound asleep. It was hoped no more than a few, intensified, Bainbridge requested maps of several scattered individuals would see the detonation, but what possible locations including an army bombing range in if there were more witnesses? Knowing it might be south-central New Mexico: “This is an excellent area in necessary to offer a public explanation, two press releases every way for our purpose.”21 The range was flat, were prepared. The first stated “that an ammunition dump typically enjoyed favorable weather, was distant from had blown up,” with very little elaboration. But what if most civilians, and relatively close to Los Alamos. hazardous levels of fallout necessitated an evacuation? In General Groves also directed that Native Americans that case, the second press release explained, “that an could not be displaced; this was supposedly done to avoid ammunition dump had blown up which contained gas dealing with Secretary of the Interior Harold L. Ickes.22 shells and the people would be evacuated for 24 hours to This too made the Alamogordo Bombing Range, as it was protect them from the gas.” In the event of an evacuation, then known, ideal. Nonetheless, several other sites were most evacuees would be transported to the Trinity base also considered. Proposed test sites included the sandbar camp, which had accommodations for 450 people.27 islands off the coast of Texas, an area near Colorado’s Safety, no doubt, was a serious (and continually Great Sand Dunes National Monument, and San Nicolas evolving) consideration. It was clear that, if successful, Island, approximately 85 miles west of Long Beach, the test would produce fallout—irradiated debris that California. But ultimately the bombing range won out, would be ejected into the atmosphere as a result of the largely for its close proximity to Los Alamos and the blast. Favorable weather, it was hoped, would distribute army’s possession of the land.23 The test site was located this dangerous material at safe levels over a very wide within a particularly desolate area known as the Jornada area. Rain, on the other hand, might pull concentrated del Muerto, the Journey of Death. amounts of hazardous particles down to Earth over a Preparing the infrastructure to support Trinity proved small area, creating a serious threat to anyone below. This no trivial matter. The test, which would feature hundreds is one of the many reasons the Trinity site was selected: it of experiments, required the construction of roads, rarely rains. bunkers, towers, auxiliary structures to support shot There was no precedent for Trinity, so a rehearsal test diagnostics, and a camp. Many ranching families who was scheduled for May 1945. Approximately 100 tons of held leases on the land were promptly evicted so that TNT were carefully stacked on a 20-foot wooden tower— work could begin in fall 1944. Like Los Alamos, the a scaled-down version of the 100-foot tower from which facilities at the Trinity site were continually expanded. the gadget would be detonated. Shortly before the 100- Hundreds of men working for multiple contractors hastily ton test, as it became known, was conducted, an irradiated transformed the area into a massive, makeshift laboratory slug was shipped to the Trinity site from Hanford, the for Oppenheimer’s scientists and engineers. For instance, Manhattan’s Project’s plutonium production plant in 200 workers employed by an Albuquerque construction Washington State. Once at Trinity, the slug was dissolved firm worked 30 days straight in spring 1945. Following a into liquid form and pumped into a tube that was short break, they worked another 30 days straight, then interwoven throughout the TNT.28 Studying the dispersal repeated the cycle once more in the weeks leading up to of the radioactive material after the explosion would offer the test. Ted Brown, the proprietor of the company, had the scientists insight into the possible scale and danger of taken on government projects before, but nothing quite Trinity’s fallout. like this. The secretive undertaking was “hotter than At 4:37 in the morning of May 7, the TNT was anything we had ever gotten hold of,” he relates, but detonated. The blast momentarily illuminated the neither Brown nor his workers were told the true purpose surrounding area, its shock thundering across the test site, of the site.24 Like a vast majority of the individuals who but the test was nearly unnoticed beyond the borders of made Trinity possible, they didn’t need to know. the bombing range. Unfortunately, the TNT detonated a The Manhattan Project was perhaps history’s largest, quarter-second early because of a rogue electrical signal, most secretive undertaking. There were notable security which resulted in a loss of data.29 However, the test breaches, such as the four spies at Los Alamos,25 but on allowed scientists to calibrate diagnostic instruments the whole, security officials managed an impossible task more precisely and better prepare for possible remarkably well. But how could a blast “as bright as a radiological hazards after the full-scale test. Louis thousand suns” be concealed?26 The remoteness of the Hempelmann, a close associate of Oppenheimer’s who test site provided some insulation, but if the test produced was charged with radiological safety, estimated 98% of an appreciable yield, the fireball would, albeit briefly, be the Hanford material was thrown into the sky, a much

3 Submitted to ANS/NT (2021), LA-UR-21-21007 higher percentage than predicted. The smoke plume HE, and the precious plutonium could have been easily carried much of it to 15,000 feet very quickly, and recovered. Bainbridge remembers, “Jumbo represented to remnants of the cloud remained visible for hours after the many of us the physical manifestation of the lowest point test. A year later, Hempelmann concluded, “It is felt that in the Laboratory's hopes for the success of an implosion there was very little likelihood of any contamination ever bomb. It was a weighty albatross around our necks.”37 reaching the earth.”30 It’s clear Oppenheimer felt the same The fascinating story of Jumbo is told in this issue by way. About three weeks before Trinity, he wrote, “even Morgan.38 the most extreme assumptions indicate that no Another significant pretest was scheduled for July 14 in community will be exposed to lethal or serious doses of Los Alamos. Physicist Edward Creutz would oversee this radiation and it is my opinion that no personnel outside of experiment, which soon bore his name. The objective was the area controlled by us will in fact be measurably to assess a full-scale implosion for the first time by exposed.”31 Nonetheless, planning for a possible imploding a gadget identical to the device earmarked for evacuation continued in the early summer of 1945, and an ground zero. Of course, there was one significant evacuation detachment was formed. It included 144 difference between the two—the Creutz device lacked soldiers who had access to 140 vehicles, 500 gallons of plutonium. Unfortunately, there were not enough quality drinking water, rations, and other supplies.32 blocks of HE available for both the Creutz and Trinity HE Approximately nine hours before the 100-ton test, assemblies, which were to be prepared simultaneously Germany surrendered unconditionally. Though fighting within different technical areas at the Laboratory on July came to an end in Europe, the war continued in the 12.39 Many of the flawed blocks on hand had air gaps Pacific. As the Battle of Okinawa raged, preparations within the HE; it was feared these gaps might affect the continued for Trinity back in New Mexico. Many symmetry of the implosion, thus compromising the construction projects had been completed. There were detonation. To make these pieces useable, George now three bunkers for witnessing the test: the main Kistiakowsky personally intervened. He recalls, “I got photography bunker 10,000 yards north of ground zero, hold of a dental drill and, not wishing to ask others to do another photography bunker 10,000 yards west, and the an untried job . . . spent most of one night . . . drilling main control bunker 10,000 yards to the south (S10,000). holes in some faulty castings so as to reach the air The base camp (which was 17,000 yards from ground cavities.” The amateur dentist then “filled the cavities by zero) had been expanded, hundreds of miles of diagnostic pouring molten explosive slurry into them, and thus made cables had been placed, and dozens of miles of roads the casting acceptable.” Apparently unfazed by the constructed. And although the 100-ton-test tower no potential danger, Kistiakowsky added, “You don’t worry longer existed, it was survived by two steel cousins. The about it . . . if fifty pounds of explosives goes off in your gadget would be detonated atop a 100-foot tower, the lap, you won’t know it.”40 Both HE assemblies were lower portion of a common 200-foot Blaw-Knox radar nearly ready to be destroyed. tower.33 But why a tower? There is surprisingly little It took months to prepare the Trinity site, but the information pertaining to why a tower was used. Ben gadget’s stay there would last just a few days. For safety, Benjamin, one of the Trinity photographers, attributed the the device was shipped from Los Alamos in two parts: the idea to his group leader, Julian Mack. Mack supposedly HE assembly and the pit, which included about 6 convinced Bainbridge that a tower would help ensure kilograms of plutonium.41 The pit made the trip to the site clear photos of the expansion of the fireball, photos that in the back seat of an army car on Thursday, July 12, would be used to help determine yield, among other escorted by one of Oppenheimer’s former students, Philip things.34 Bainbridge offers another hint: “It was important Morrison.42 Upon arrival, it was prepared by G Division to study the blast effects under conditions that could be engineers at the McDonald ranch house, the former translated into combat use conditions to obtain the residence of a recently evicted ranching family. Shortly maximum military effect of the bomb.”35 If the gadget after midnight on Friday, July 13, the HE assembly were set off on the ground, many important blast followed, making its long, slow journey southward measurements would be skewed. accompanied by Kistiakowsky and Norris Bradbury, a The other tower was designed to support a 214-ton steel Stanford physics professor and Naval Reserve containment vessel called Jumbo. The vessel, which was Commander.43 In the afternoon of the 13th, Bradbury manufactured by Babcock & Wilcox in Ohio, was presided over the gadget’s assembly at the base of the designed to contain the blast of the Trinity device’s tower under Oppenheimer’s close supervision. conventional explosives.36 In the event Trinity was Two of the G Division engineers, Harry Daghlian and successful, Jumbo would have most likely been Louis Slotin, monitored radiation levels as their vaporized. But had Trinity failed to produce a nuclear colleagues attempted to insert the pit into the center of the explosion, Jumbo would have contained the blast of the device through a canal in the HE. Daghlian and Slotin,

4 Submitted to ANS/NT (2021), LA-UR-21-21007 shown in Figure 1, ensured the HE itself would not reflect enough neutrons toward the plutonium to produce a prompt critical reaction, which would have delivered enormous—possibly lethal—doses of radiation to everyone in the immediate area. Though radiation levels remained safe, the stubborn pit refused to travel all the way past the HE to heart of the gadget. The pit had swollen slightly due to thermal expansion caused by the desert heat and the plutonium itself. The nature of the problem was quickly recognized; the assembly team simply allowed the pit to cool in the shade of the canal. After a few minutes, the plutonium contracted and its journey resumed.44 With the pit now resting deep within the bomb, Bradbury personally closed the canal by inserting the final blocks of HE, thus completing the tense operation.45 Tragically, Daghlian would be dead just two months later, the world’s first victim of a fatal criticality accident. Slotin died in the same horrific manner less than a year later on May 30, 1946, exactly one month before the world’s second nuclear test, Crossroads Able. Back when Los Alamos was under construction in the late winter of 1943, Oppenheimer was already contemplating the possibility of a dud. On the back of a March 11 letter, shown in Figure 2, from his private trust officer, the director scribbled, “What are the probabilities of a fizzle? Of a failure?”46 Uncertainty had been a constant companion of many project scientists, and it lingered in the days before Trinity. Norman Ramsey, for instance, supposedly at one point bet the yield would be zero.47 He wasn’t alone. The initial results of the Creutz test were discouraging—it appeared the implosion would not be powerful enough to drive a runaway chain reaction. Hans Bethe, the calm and sage leader of the Theoretical Division, who like Ramsey, would later win a Nobel Prize, reviewed the data more carefully in the hours following the test. Although he concluded Trinity would most likely be successful after all, the damage to the staff’s psyche was done. To assuage Oppenheimer, his frazzled and emaciated boss, Kistiakowsky proposed a Figure 1. Top: Commander Norris Bradbury (right) leads the wager: “I offered him a month’s salary against ten dollars assembly team beneath the tower. Center: (left to right) Herbert that our implosion charge would work.”48 Ramsey and Lehr, Harry Daghlian, Louis Slotin, and Marshall Holloway Oppenheimer’s confidence must have been chipped away continue the assembly process; both Daghlian and Slotin would be dead just months later. Bottom: Oppenheimer supervises final by reminders of even less certain times. For instance, preparations before the gadget is hoisted to the top of the tower. Jumbo loomed just 800 yards from the main tower—a monument to doubt. Though Jumbo and the other Emil Konopinski demonstrated that it could not happen. plutonium recovery methods had been abandoned in Still, with Trinity just hours away, Laboratory associate March, a time when both confidence and plutonium director and 1938 Nobel Prize recipient Enrico Fermi production rates were rising, the steel behemoth must jokingly took bets on if a successful test would destroy have remained to some a very tangible and unwelcome the world.50 Initially, General Groves, who was now harbinger of potential catastrophe.49 present at the bombing range, was not pleased. But he The possibility of even greater catastrophe had been later changed his mind: “Afterwards, I realized that his suggested early on—might a nuclear detonation set the talk had served to smooth down the frayed nerves and Earth’s atmosphere on fire? Physicist Edward Teller ease the tensions of the people at base camp.”51 And proposed the idea in 1942, but Bethe and, later, physicist

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Figure 2. In the closing days of winter 1943, as Los Alamos was under construction, Oppenheimer made this list of key questions that would need to be answered in order to build nuclear weapons. These include, “What is present knowledge of critical masses?,” “What methods are considered for detonation?,” and “What are the probabilities of a fizzle? Of a failure?”

6 Submitted to ANS/NT (2021), LA-UR-21-21007 indeed, tensions were high, in part because of Groves’s bitter toward Hubbard, writing in 1970: “Our weather order for the test to be conducted on the 16th. President expert, who had been highly recommended by a leading Harry S. Truman was about to meet with Soviet dictator technical school, just didn’t make a sound prediction,” Joseph Stalin at Potsdam, Germany, to discuss the fate of continuing, “I had previously become a little disturbed postwar Europe and the status of the war in the Pacific: it about his capabilities and had sent in only a few days was necessary to let the president know if the US had before, in an advisory capacity, one of the best forecasters harnessed the unimaginable power of the atom before the Army had.” But the General lamented, “I should have negotiating with one of history’s most prolific mass done it sooner.”57 Nonetheless, around 4:45, Bainbridge murderers. Come what may, the test would not be received Hubbard’s final prediction: “at 5:30 a.m. the postponed.52 weather at Point Zero would be possible but not ideal.” The morning of the 14th, at roughly the same time the On this basis, senior leaders decided to proceed at that Creutz test was conducted in Los Alamos, the gadget time.58 began its one-way journey to the top of the tower. That afternoon, within the tight confines of the shot cab, IV. Let There Be Light Bradbury and his colleagues emplaced and wired the Shortly after arriving at the S10,000 control bunker, gadget’s 32 detonators.53 With his work largely done, Bainbridge initiated the firing procedure: “I unlocked the there was only one activity for the 15th scheduled on master switches and McKibben started the timing Bradbury’s checklist: “Look for rabbit’s feet and four sequence at –20 minutes, 5:09:45 a.m. At –45 seconds a leafed clovers.” There was only one activity scheduled for more precise automatic timer took over.”59 Over 400 the 16th, as well: at 0400, “BANG!”54 Work remained for official spectators would observe the unique display from others, however. As the 15th drew to a close, the arming various locations. The senior scientists playing prominent party traveled to the tower; those who made the trip roles in conducting the test would, for the most part, be in included Bainbridge, Kistiakowsky, physicist Joseph the bunkers. Many other senior scientists would watch the McKibben, chemist Donald Hornig, four soldiers, and spectacle from Compania Hill, which was located 20 meteorologist Jack Hubbard. Hornig completed the miles northwest of ground zero near New Mexico process of connecting the bomb to the live detonating unit Highway 380. There, in the darkness, Teller and several during his long, lonely guard shift in the shot cab. He was colleagues applied suntan lotion to protect against the the last person to see the gadget.55 Although Hornig did blast.60 General Groves and his small entourage of VIPs, not encounter saboteurs, another dreaded foe made an which included Vannevar Bush (head of the Office of appearance—rain. “The possibility of lightning striking Scientific Research and Development) and James Conant the tower was very much on my mind,” Hornig recalls, (chairman of the National Defense Research Committee), but since the tower was properly grounded there was prepared to witness the test at the base camp, which had almost no chance of an accidental detonation.56 The very dodged most of the rain.61 Observers there were instructed serious issue of fallout reemerged, however, and along to “lie prone on the ground or in an earthern [sic] with it a terrible conundrum. If Trinity were detonated on depression, the face and eyes directed toward the south.” schedule at 4:00 a.m. in the middle of a storm, the After the light of the blast illuminated the surrounding precipitation would guarantee much of the surrounding mountains, they could look toward ground zero though a area would be heavily contaminated. If Trinity were welder’s filter. They were warned that it would take postponed, the president would enter the first day of approximately 50 seconds for the shock wave to arrive, negotiations at Potsdam without knowing if the US and that they should remain on the ground until it possessed a nuclear capability. Both of these passed.62 There would be no more delays. Conant is said unacceptable options were eventually discarded. to have uttered, “I never realized seconds could be so Fortunately, there was another option, albeit another long.”63 undesirable one. If the test were delayed until the storm Those seconds were particularly agonizing for the Los passed, a significantly higher number of local residents Alamos director. There in the S10,000 bunker, in the would be stirring and might catch a glimpse of the secret moments before detonation, Oppenheimer purportedly operation. However, this option would greatly improve said, “Lord, these affairs are hard on the heart.”64 One of the safety outlook and enable General Groves to pass his many companions in the crowded bunker, physicist along news of a successful test (or fizzle) to the president. Samuel K. Allison, conducted the final countdown over Thus, security was sacrificed for safety and the demands the public address system. Allison’s broadcast, which was of international politics. Hubbard had the unfortunate relayed back to base camp over the radio, was apparently duty of briefing the weather situation to Oppenheimer, disrupted by interference from other signals. One who remained on edge, and Groves, who was even more divergent but supremely appropriate tune accompanied agitated than usual. Even after 25 years, Groves remained Allison’s performance—The Star Spangled Banner.65 As

7 Submitted to ANS/NT (2021), LA-UR-21-21007 the countdown entered the final 45 seconds, only two Trinity’s fireball vaporized much of the tower, things could stop Trinity: the young chemist Don Hornig, shattered the remaining portions into tiny fragments, and who now manned the “knife switch” in the bunker, or a created a 5-foot-deep, 30-foot-wide crater at its base.74 malfunction.66 Hornig nervously awaited the command to The reinforced concrete footings of the tower, which had abort, but it never came. As Allison concluded his count, largely been underground, were exposed as the fireball he shouted, “Now!”67 That morning, at 5:29:15, the absorbed earth to form the crater. The blast shattered the world’s first nuclear detonation signaled the beginning of upper portions of the concrete, leaving only the heavy, a new era in history.68 The Jornada, still rich with the mangled rebar behind as a testament to the destructive scent of saturated creosote bushes, momentarily hosted force of the test. Scientists correctly predicted hundreds the most brilliant flash the world had ever known. It was of tons of earth would be consumed by the fireball, which approximately thirty minutes before the dawn. reached nearly 15,000 degrees.75 Some of the radioactive More than 50 cameras officially documented Trinity. material would attach itself to the dirt: smaller particles Fastax cameras, some operating at thousands of frames would rise into the atmosphere in the form of smoke and per second, recorded the expansion of the early fireball. heavier, molten particles would quickly fall back to the Spectrographic cameras, Mitchell cameras, and relatively surface.76 Once on the surface, the molten material simple pinhole cameras also successfully gathered data. solidified as temperatures cooled, forming the greenish, The only color photograph of the test was taken by Jack glasslike mineral trinitite. Mercer et al.77 describe how Aeby, one of Segre’s technicians, but despite the striking researchers continue to study Trinity’s radioactive debris nature of his and many other images, none truly captured in trinitite. the absolutely breathtaking nature of Trinity. For many, the blast was not a merely a time to admire, Some of the most memorable lines describing the test but a unique opportunity for discovery. Of the hundreds were penned by the project’s embedded reporter, William of experiments performed during Trinity, perhaps the Laurence. The Lithuanian-born future Pulitzer Prize most famous—and likely the least complex—was winner wrote, “It was as though the earth had opened and performed by Fermi. It took about 40 seconds for the the skies had split. One felt as though he had been shock wave to reach him at the S10,000 bunker. When it privileged to witness the Birth of the World—to be did, Fermi “tried to estimate its strength by dropping from present at the moment of Creation when the Lord said: about six feet small pieces of paper before, during and Let There be Light.”69 In the case of Trinity, Laurence’s after the passage of the blast wave.” He noted the force of unmistakably hyperbolic style is probably warranted. the blast shifted the pieces of paper “about 2½ meters, Roger Rasmussen, a member of the evacuation which, at the time, I estimated to correspond to the blast detachment, assigned human traits to the fireball. Like that would be produced by ten thousand tons of T.N.T.”78 others, he noted the many colors produced by the blast, Fermi’s estimate was only off by a factor of 2, which is but added, “I thought it looked angry.” Rasmussen was quite impressive considering the only measuring initially awestruck by the silence, but eventually the instrument he had at his immediate disposal was a blank shock wave arrived. On the 70th anniversary of Trinity, piece of paper. Katz’s paper79 in this issue attempts to he stated, “I think the world blew-up about then . . . it’s understand how Fermi might have done this. The different startling even today.”70 Morrison, the pit’s escort, approach of G. I. Taylor, who used the fireball growth to witnessed the blast from base camp. Despite being 10 determine a yield, is considered by Baty and Ramsey.80 miles from ground zero, he remembers, “The thing that Yet, Trinity was so much more than just another got me was not the flash but the blinding heat of a bright science experiment, and the diverse audience it attracted day on your face in the cold desert morning,” continuing, responded to the phenomenon they had witnessed in very “It was like opening a hot oven with the sun coming out different ways. Oppenheimer’s ethereal final assessment like a sunrise.”71 has become synonymous with the test. Twenty years after Even 75 years later, the gadget’s yield is still being Trinity, the gaunt former director, who was then nearing evaluated. Since 1945, the field of nuclear radiochemistry the end of his life, recalled, “We knew the world would has advanced in its assessment of Trinity’s total yield. not be the same. A few people laughed. A few people Hanson and Oldham describe this progression elsewhere cried. Most people were silent.” Oppenheimer continues, in this issue.72 The first radiochemical assessment was “I remembered the line from the Hindu scripture, the about 18 kilotons of TNT, a value that exceeded many Bhagavad Gita. Vishnu [sic] is trying to persuade the people’s expectations. Later, the DOE released their still prince that he should do his duty, and to impress him takes current official assessment of 21 kilotons, and now in this on his multi-armed form and says, ‘Now I become death, issue, Selby et al.73 describe Los Alamos’s latest the destroyer of worlds.’ I suppose we all thought that, assessment of 24.8 ± 2 kilotons based on some advances one way or another.” Oppenheimer, of course, did not see in high-precision mass spectrometry. himself as the multi-armed Hindu god of war—he saw

8 Submitted to ANS/NT (2021), LA-UR-21-21007 himself as the prince, who was obliged to do his duty.81 News of Trinity spread quickly. Secretary of War Frank Oppenheimer, Robert’s brother and the chairman Stimson, who was at Potsdam with Truman, received of the Trinity safety committee, was with him at the news of the successful test hours after the explosion. A S10,000 bunker. He remembers, “I think we just said, ‘it coded telegram reported, “Operated on this morning. worked.’ I think that’s what we said, both of us, ‘it Diagnosis not yet complete but results seem satisfactory worked,’ and nobody knew it was going to work.” Isidor and already exceed expectations. Local press release I. Rabi, a 1944 Nobel laureate and consultant at Los necessary as interest extends great distance. Dr. Groves Alamos, reports, “[Oppenheimer] came to where we were pleased.”90 The test was reported in New Mexico as well. in the headquarters . . . his walk was like high noon. I Trinity could not be concealed, prompting the bombing think it’s the best I could describe it, this kind of strut. range to issue the carefully prepared press release. The He’d done it.”82 next day, on July 17, the Associated Press ran a story that There were many other notable reactions as well. appeared in newspapers throughout the region: Perhaps the most lighthearted quote pertaining to Trinity “Following a blast felt over hundreds of miles Monday came from Kistiakowsky, who had not forgotten the morning, explosion of ‘a considerable amount of high wager he made following the Creutz test. After the blast explosive and pyrotechnics’ in a remote area of the wave passed, “I slapped Oppenheimer on the back and Alamogordo air base reservation was reported by Col. said, ‘Oppie, you owe me ten dollars.’”83 Unable to pay William O. Eareckson, commandant.” According to the up on the spot, Oppenheimer later presented story, the explosion was detected in Gallup, New Mexico, Kistiakowsky with a signed 10 dollar bill during a more than 200 miles northwest of the test site. Despite the meeting at the Laboratory.84 In discussing Trinity years magnitude of the event, “there were no loss of life or later, the ever-candid Norris Bradbury stated, “For me to injury to anyone.” In the story, which made the front page say I had any deep emotional thoughts about Trinity . . . I of the Albuquerque Journal, various witnesses guessed didn’t. I was just damned pleased that it went off.”85 There the incident was caused by an exploding bomber, a were no official female observers at the bombing range, crashing meteor, or an earthquake.91 There would be no but women witnessed the test nonetheless. Marge evacuation to report. Bradner, one of Oppenheimer’s secretaries, viewed the test from a position in the Sandia Mountains V. The New Hazards of a New Era approximately 100 miles from the bombing range: The quickly prepared safety plan for Trinity was “Words cannot describe the emotions, joys and fears that reasonably thorough, fairly elaborate, intentionally filled all of us who witnessed this first atomic bomb in the flexible, and in hindsight, somewhat lacking. Attributed New Mexico desert. The spectacle was tremendous, to Hempelmann, the plan suggested a specific exposure beautiful, magnificent, terrifying, exciting, humbling, limit for project participants: “It has been advised that no scary.”86 person should (of his own will) receive more than 5 R Ben Benjamin also considered the blast beautiful, but [roentgens, the common unit of measuring radiation at his boss Julian Mack did not share the sentiment. “No, it’s that time] at one exposure.” The upper dose limit over a terrible,” Mack immediately retorted, later explaining, two-week period was set at 75 R by Dr. Hempelmann, “Well, I was just thinking of the moral implications of Colonel Stafford Warren (chief medical officer of the what we were doing here and how a lot of people were Manhattan Project), and Warren’s deputy, Lt. Col. Hymer going to look at this.”87 Victor Weisskopf, a physicist who Friedell, during a conference at base camp on July 14.92 helped develop safety precautions for viewing Trinity, For perspective, today a Department of Energy worker is succinctly described the range of emotions that followed limited to approximately 5 R over the course of a year.93 the test: “Our first feeling was one of elation, then we For civilians, “Evacuation of towns or inhabited places realized we were tired, and then we were worried.”88 The will be carried out by G-2 personnel if necessary on journey back to Los Alamos was apparently a somber advice from the Medical Department.”94 That morning one. Unable to sleep, many exhausted scientists the three doctors, in consultation with Hubbard and a few contemplated their invention being used in calamitous other colleagues, also established the threshold for an wars of the future. Stan Ulam, the soft-spoken Polish evacuation: “The upper safe limit of radiation raised to 15 mathematician who would later play a prominent role in r/hr at peak of curve.”95 devising the hydrogen bomb, chose not to attend the test; Perhaps the most significant postshot hazard for onsite he remained at Los Alamos. When his colleagues arrived Trinity participants was reentering the test area to retrieve at the Laboratory, he noted, “You could see it on their technical equipment and to collect materials for faces. I saw that something very grave and strong had radiochemical analysis. About 90 minutes after the test, happened to their whole outlook on the future.”89 an M4 Sherman tank lined with 11,000 pounds of lead lurched toward ground zero to collect samples from the

9 Submitted to ANS/NT (2021), LA-UR-21-21007 crater. Physicist Herbert L. Anderson, who estimated that this is done we can not [sic] be responsible for the health the tank’s occupants would be subjected to only one- interests of the visitors.”103 It was another fiftieth of the radiation, thanks to the lead shielding, was recommendation. It is clear the Health Group possessed aboard.96 The measurements taken by Anderson and his no real authority. colleagues contributed to the creation of a map that showed radiation levels throughout the immediate test area.97 This map would help project scientists remain under the 5 R limit recommended by the safety plan. Despite the attention paid to onsite safety, the crater itself became somewhat of a tourist attraction in the weeks and months that followed. Even before the war was over, Lt. Jerry Allen complained of “entirely too many groups entering the contaminated area at TR.” Many of these visitors claimed to be recovering equipment, but it appears they may have been more interested in collecting trinitite souvenirs.98 The most famous postshot visit came the following month, when the press was invited to tour ground zero one week after Japan’s formal surrender. It was during this visit on September 9 that the famous photograph of General Groves and Oppenheimer was taken near the remains of the tower footings. Guests, who wore protective coverings over their shoes, were allowed to remain in the area for 30 minutes. Certain areas of the crater were still quite radioactive, producing readings as high as 7 R/hour. Thus, the maximum dose that could have been received by a visitor during that one exposure was 3.5 R, which would have been supplemented by the small pieces of trinitite they were allowed to take. Oppenheimer personally warned “that keeping the samples,” which could read no more than 0.03 R/hour, Figure 3. Julian Mack and his children pose next to the Jumbo vessel, April 20, 1954. “continuously close to the skin for a month might be dangerous.” Hempelmann estimated the reporters likely Offsite, another story unfolded. For most scientists, the 99 received an average dose of 1 R during the visit. hours following Trinity were a time of cathartic But even after the reporters left, the tours continued. In reflection. But Joseph Hoffman, leader of the offsite October, many scientists brought personal guests to monitoring team, would supervise a frenetic, high-stakes experience the birthplace of the nuclear age. For instance, drama that would take place over hundreds of square there are several documented cases of scientists bringing miles. Hoffman carried a significant burden—he was the along wives, and even cases of children visiting ground only individual officially authorized to call an 100 zero. Figure 3 shows Julian Mack posing in front of evacuation.104 Two days before the test, he finalized plans Jumbo with his children years later, though similar visits for his group of radiation monitors, who would travel in happened in the months following the test. Two pairs, making careful measurements of radiation levels University of New Mexico professors were also allowed along their prescribed routes. Most of the teams would to spend an hour in the crater collecting samples on provide Dr. Friedell, who would be based in 101 October 30. In the midst of these visits, Hempelmann Albuquerque, with hourly updates; the teams near issued more suggestions, such as, “It is my feeling that no Carrizozo and Socorro would provide updates every half- one should enter the fenced off contaminated area except hour, as those were considered the most at-risk population for scientific purposes.” Though his letter included some centers. The detailed plan also tasked specific monitoring directions of a firmer nature, Hempelmann concluded, teams with the responsibility of evacuating specific “Unless you hear from me to the contrary I would suggest families should the need arise. In addition to the roving 102 that the above instructions be put into effect.” monitors, there were also fixed instrument stations at Apparently, the doctor’s plea accomplished little, as the Magdalena (NW), San Antonio (NW), Socorro (NW), visits continued. In December, one of the military doctors, Carrizozo (E), Tularosa (SE) and Hot Springs (SW).105 Captain Harry O. Whipple, requested that all visit Data was collected in other ways, as well: registered requests officially go through the Health Group: “Unless

10 Submitted to ANS/NT (2021), LA-UR-21-21007 letters containing film badges were sent to dozens of post R/HR, this figure being dangerously close to the offices all over the state. Only five badges recorded doses evacuation limit.”113 McElwreath and his monitoring higher than 0.1 R: Encino (0.3), Duran (0.4), Pedernal partner, Sergeant Robert Leonard, immediately drove to (0.6), Bingham (3.3), and Cedarval (6.3).106 Simon et al. Hoffman’s location nearby to report the reading. recently analyzed these badge data in a National Cancer Interestingly, as radioactive material began to drift back Institute (NCI) study (see Fig. 6 of Ref. 107). to Earth in greater amounts, and as communication Although the data was collected for safety and between the monitors began to break down, Hoffman scientific purposes, it was also gathered for possible personally recorded 15 R/hour seven miles east of litigation. At the request of the project’s claims officer, Bingham at 9:05 a.m. The area east of Bingham reached Hempelmann directed Hoffman and his monitors to “keep “90 percent of tolerance,” but because “high readings” as complete notes as possible in your own handwriting to were “in uninhabited areas,” there would be no be signed and filed away by you for future reference. evacuation.114 Back at ground zero, the Trinity crater was These notes can be written up more fully at a later date still at a staggering 800 R/hour the day after the test.115 but in any court proceeding it is necessary to have your Though relatively trivial, measurable amounts of original data.” Hoffman was also informed, “You will be radiation were recorded at Los Alamos. An anonymous, the chief witness for off-site contamination.”108 The handwritten trip report prepared on July 18 noted, “It is Cornell physicist, however, was never called to testify. evident that there is radiation on the mesa at Site Y. It is From the standpoint of weather, July 16 was not an about .0015 R/hr.”116 Figure 4 shows a modern map of the ideal day to perform the test. In addition to the rain, wind exposure rates. 117 direction remained unpredictable in the days leading up to Trinity. That morning, searchlight crews stood ready to illuminate the cloud so it could be tracked in the darkness, but with the sun rising, the lights were not needed. Captain Marvin Allen’s report on the activities of the searchlight crews noted, “During ascent the cloud broke into three distinct groups, the lower one drifting north, the center one drifting west, and the top one drifting northeast.”109 Eventually, the top portion of the cloud rose to a height between 45,000 and 55,000 feet and moved to the northeast at 14 miles per hour. For the first 10 to 15 miles from ground zero, there was little radioactive material, but beyond that, there was an area approximately 100 miles long and 30 miles wide with varying degrees of detectable contamination. It was estimated that the inhabitants of a ranch house within this swath, near the tiny hamlet of Bingham, may have received a dose of 60 R over the following four-week period.110 Hoffman estimated between 1 and 10 percent of the hazardous material ejected into the air as a result of the blast reached the ground in the first 24 hours, a lower rate 111 than initially supposed. Throughout much of the Figure 4. Map of exposure rates (mR/hour) normalized to 12 region, radiation levels remained very, very low. hours after the Trinity test. The dark spots are cities with However, there were some notable exceptions. At 8:30 populations of at least 10,000. This map from the NCI is a synthesis of several datasets, as described in the source article a.m., three hours after detonation, John L. Magee 117 recorded 20 R/hour approximately 20 miles northeast of by Bouville et al., and was used in the risk projection study of public exposure to Trinity fallout by Simon et al. 118,119 recently ground zero in a canyon near a ranch owned by the Ratliff published in Health Physics. Used with permission of the NCI. family. Originally known as Hoot Owl Canyon, this now infamous landmark was given a new name by the Higher measurements were recorded near the ground, scientists immediately after the test—Hot Canyon.112 At where radioactive material collected. At torso level, the roughly the same time Magee made his measurement, dose dropped, often significantly. Time was also a critical Special Agent William McElwreath of the variable for safety. Radiation levels increased as Counterintelligence Corps noted, “At a point 4 miles east radioactive materials fell from the sky; however, many of of Bingham New Mexico a reading was indicating 6.5

11 Submitted to ANS/NT (2021), LA-UR-21-21007 these materials had very short half-lives and remained had the appearance of being covered with light snow or potentially dangerous for only a matter of hours. It is of being ‘frosted’ for several days after the shot.”126 In estimated that Bingham, for instance, absorbed a total addition to the dogs, two of the Ratliff cows suffered mild ground dose of 27.3 R (8.1 R torso) over the course of two injuries. That same month, November 1945, the weeks. The area surrounding Hot Canyon fared far more government purchased four animals from nearby ranches poorly: 139 R ground dose (56 R torso).120 The Ratliffs— for study.127 In December, Hempelmann returned to the a husband, wife, and their young grandson—lived area with orders from Washington “to buy all damaged approximately one mile from Hot Canyon. Although cattle that the ranchers wanted to sell.” A total of 75 government officials had made an effort to plot the animals were purchased from two ranches. The 14 locations of all the area’s inhabitants, the Ratliffs were not (possibly 17) most-injured animals were sent to Los discovered until the day after the test. Friedell and Alamos for observation, and the remaining cattle were all Hempelmann found the family, but “Decided temporarily sent to Oak Ridge. Hempelmann believed the most- against evacuation because of relative low radiation damaged animals were poorly nourished and likely had intensity.”121 Warren, Whipple, and Hempelmann noted been trespassing on the bombing range at the time of the it rained the evening of the 16th and reported, “this means test.128 One of Hempelmann’s colleagues, Dr. Robert that some of the activity was carried into their drinking Stone, estimated the average, approximate dose required water and may have been drunk on the following day and to inflict such injury at 20,000 R of beta radiation to the thereafter.”122 Over the six-week period following the skin over an undisclosed amount of time.129 test, Hempelmann estimated that the Ratliffs received a The Los Alamos herd was observed and successfully total dose of 49.4 R.123 A notable dose, but far below the bred over the next few years.130 Hempelmann authorized 75 R two-week limit established before the test. the release of the original animals in 1948, only keeping In the following months and years, visitors from Los a handful of calves for continued observation. One of Alamos and the army would periodically visit the Ratliffs Hempelmann’s successors, Dr. Thomas L. Shipman, and other ranching families in the area. After the atomic inherited these animals. In 1950, he informed the Los bombing of Hiroshima, when the secret nature of Trinity Alamos area manager that the Health Division no longer was revealed, a relatively young man living near the had a need for them. Shipman thoughtfully offered to help bombing range whose hair was turning gray publicly liquidate the herd: “I have a personal interest in obtaining blamed fallout from the test for the premature change. one or more of these animals for the purpose of However, neighbors revealed the man had a secret of his augmenting my family beef supply.”131 Thus ended the own: months before the test, he attributed the change to Laboratory’s brief foray into the cattle business. dehorning paste, which he inadvertently applied to his Given the limited knowledge of radiation-protection face. “According to the neighbors,” the young rancher principles possessed by Los Alamos scientists at the time, was, “having fun at the expense of the newspapers.”124 competing priorities such as international politics and Visits to ranches in the area continued despite the baseless security, and significant time restraints, it is both hoax. In June 1947, two Los Alamos employees, Charles impressive and fortunate that Trinity was conducted as Blackwell and George Littlejohn, visited several ranches safely as it was. But that is not to say there were no in the general vicinity of Carrizozo. At one of the ranches, problems. For instance, although it was not widely their colorful account notes, “a young lady met us at the reported publicly until 1949, radioactive debris from door with an explanation on how to find the French Trinity’s fallout contaminated cardboard used to package Ranch,” continuing, “after a quick three hour check of this Kodak film. Over a two-week period, beta radiation young lady we concluded if radiation produces this type produced by 240Ce caused blotches to appear on the of loveliness, several of the girls I go with should be film.132 At the local level, there were deficiencies in the promptly ushered into the Trinity crater.”125 Blackwell monitoring plan as well. An informal memo noted the and Littlejohn failed to detect any radiation at the ranch. communication problem: “Headquarters in Albuquerque Although there were no obvious injuries to humans, apparently failed in its function to direct monitors.” At there were injuries to animals. For instance, the Ratliffs’ Bingham, a member of Hoffman’s team “violated the four dogs all suffered from maladies after Trinity. That monitoring program” by telling “the monitors it was a November, Hempelmann noted the two house dogs waste of time.” This incident led one monitor to leave the developed limps: “This progressed for several weeks until area, one must assume in frustration, without further their foot pads were raw and bleeding.” Mr. Ratliff’s herd instructions. The memo also mentions that measuring dogs were both afflicted as well, developing skin equipment was easily contaminated, thus compromising problems on their backs. During the visit, the rancher told survey data.133 Decades later, Hempelmann simply the doctor and his colleagues of an interesting phenomena concluded, “We were just damn lucky.”134 he observed: “He stated that the ground and fence posts

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Seventy-five years later, there are aspects of Trinity’s Army soldiers were in Hiroshima at the time of potential health hazards that remain unresolved. In detonation.141 A day earlier, it would have taken 1500 B- October 2020, the National Cancer Institute (NCI) 29s, 15,000 airmen, and many hours—if not days—to published six articles in the journal Health Physics deliver the equivalent amount of firepower in combat. On pertaining to cancer probabilities associated with public August 6, 1945, it only took one plane, one bomb, and 12 exposure to fallout from the test.118,119 The NCI study men to destroy Hiroshima. And, unlike conventional ultimately concluded, “There is great uncertainty in the bombing, there was no effective countermeasure for estimates of radiation doses and number of cancer cases nuclear attack. The Manhattan Project had produced the possibly attributable to the test, thus no firm estimates can war’s only weapon that was simultaneously reliable, be established.”118 Although Trinity was a monumental militarily effective, and irresistible. scientific achievement, our understanding of its Late in the evening of August 8, the Soviet Union consequences continues to evolve.135 declared war on Japan. Shortly thereafter, the Red Army invaded Manchuria and Sakhalin, killing tens of VI. The Terrible Cost of Victory thousands of Japanese soldiers in the brief campaign that The gadget was not designed for deterrence: it was ensued. This catastrophic event was followed by another designed to enter combat as quickly as possible. With several hours later. The mission to Hiroshima had gone Nazi Germany destroyed, Imperial Japan continued smoothly, but the second strike proved problematic. The fighting a hopeless war. In hindsight, Japan likely never B-29 named Bock’s Car carried Fat Man to Kokura, home had a path to victory after the tactically brilliant, but to one of the largest arsenals in Japan. The crew was under strategically ill-conceived, attack on Pearl Harbor. The orders to visually acquire the target, but the city was Allies had poured a vast majority of resources into obscured by clouds. After making multiple unsuccessful defeating Hitler in Europe, and in the summer of 1945, bombing runs, Bock’s Car departed for the backup they could now concentrate exclusively on annihilating target—Nagasaki. There, shortly after 11:00 in the Japan. As the final phase of the war came into view, morning, Fat Man was released.142 The bomb detonated Trinity’s success provided hope for a quick and decisive high above the Mitsubishi Arms Manufacturing Plant, end to the conflict. producing a yield equivalent to 21,000 tons of TNT. A week into the Potsdam Conference, President Because the plant was located on the edge of town, there Truman informally told Stalin that the US “had a new were fewer casualties despite the weapon’s greater yield. weapon of unusual destructive force.” Stalin, of course, Nonetheless, nearly 40,000 died by mid-November was well aware of the existence of the Manhattan Project. 1945.143 One of his spies, Oscar Seborer, likely sat within earshot Shortly before the Nagasaki mission, three Los Alamos of Allison’s countdown in the main control bunker at physicists penned a letter to Japanese physicist Ryokichi Trinity.136 According to Truman, the Soviet dictator Sagane, a former associate at Berkeley. Morrison, Robert “showed no special interest.” Instead, he encouraged the Serber, and future Nobel laureate Luis Alvarez president to make “good use of it against the Japanese.”137 emphasized that the US had the ability to rapidly At the conclusion of the conference, a proclamation was reproduce nuclear weapons: “Within the space of three issued. It called for Japan to unconditionally surrender or weeks, we have proof-fired one bomb in the desert, face “prompt and utter destruction.”138 Unfortunately, the exploded one in Hiroshima, and fired the third this threat did not produce the desired outcome, and the war morning.” They also added a clear warning: “As continued. scientists, we deplore the use to which a beautiful On August 6, 1945, Little Boy was carried to the discovery has been put, but we can assure you that unless Japanese city of Hiroshima aboard the B-29 bomber Japan surrenders at once, this rain of atomic bombs will Enola Gay. Hiroshima was considered an important target increase manyfold in fury.” The letter was dropped from primarily because it was the home of a major military the observation plane during the Nagasaki strike, several headquarters. The weapon was dropped at 8:15 that miles from Fat Man’s detonation point. Though it was not morning from an altitude of just over 31,000 feet. To delivered to Sagane until October, the letter was maximize blast damage over a wide area, Little Boy immediately recovered by Japanese soldiers.144 detonated at approximately 1,750 feet, producing a yield The US could have made good on the threat. Although equivalent to 15,000 tons of TNT. Unlike Trinity, the no additional Little Boy units would be ready until later fireball came in contact with neither the ground nor the in the fall, many more-efficient, rapidly reproducible rising plume of ground debris, so radiation from fallout in descendants of the Trinity gadget were already on the the immediate vicinity of the blast was reduced.139 Still, way.145 The day after the Nagasaki strike, General Groves the devastation on the ground was unworldly.140 In sum, informed General George C. Marshall, the chief of staff 64,500 died by mid-November 1945; 30,769 Imperial of the US Army, that the next imploding weapon “should

13 Submitted to ANS/NT (2021), LA-UR-21-21007 be ready for delivery on the first suitable weather after 17 al.154). But the legacy of Trinity is complex and or 18 August.” By the 13th, another unit was ready to multifaceted—even after 75 years of reflection, the ship, although President Truman had ordered no unparalleled promise and peril of the nuclear age remains additional bombs to be deployed without his express impossible to fully appreciate. approval. 146 That weapon would have been followed by In the summer of 2020, the news media gave relatively three or four more in September and three more in little coverage to Trinity’s anniversary. In the midst of the October. If the Japanese government had chosen not to COVID-19 pandemic, civil unrest, and an acrimonious surrender, these weapons (with concurrence from presidential election, the test was not particularly Truman) would likely have been used in a more tactical newsworthy. However, at 5:29 a.m. on July 16, 2020, a manner.147 solemn ceremony was held at ground zero. White Sands Fortunately, the third weapon never left the continental Missile Range Commander, Brigadier General David United States because an armistice was announced on Trybula, shown in Figure 5, was able to discuss the test August 14. No single event produced the victorious openly, unlike his distant predecessor Colonel Eareckson. outcome. Rather, years of battlefield defeats, “Trinity was the result of the fusion of the collective conventional bombing, atomic bombing, the Soviet entry experiences of thousands of people who sacrificed their into the war, the blockade, the threat of invasion, an time and lent us their expertise to create something attempted palace coup in Tokyo, and other factors remarkable,” the general remarked.155 Approximately collectively drove the Japanese to surrender half a million people worked for the Manhattan Project at unconditionally.148 The role that each of these variables one point or another during its existence—people from all played will likely be debated for generations, but there is over the United States and from countries near and far. no doubt the use of the atomic bombs was a key element. This aspect of Trinity’s legacy is often overlooked: For instance, the Japanese emperor specifically alluded to despite the adversity of those dark times, a diverse cast of the atomic bombs in his address to the nation on the 14th: hundreds of thousands labored together to change the “Moreover, the enemy has begun to employ a new and world. In this time of strife 75 years later, Trinity can most cruel bomb, the power of which to do damage is provide inspiration for a country that is deeply, bitterly, indeed incalculable, taking the toll of many innocent and unnecessarily divided. lives.”149 That same day William J. Donovan, director of Long before Trinity, there were collaborations among the Office of Strategic Services, sent a top-secret the government, private industry, and academia. memorandum to Truman informing him that the Japanese However, the Manhattan Project required these entities to diplomats at the embassy in Switzerland were “extremely collaborate on an unprecedented scale. The project angry at the USSR,” and they believed “that the atomic established a template that would pave the way for bombs, not the Soviet entry into the war in the Pacific, massive programs of the future, such as the Apollo caused the Japanese offer to surrender.”150 The Soviet Program and the Human Genome Project, as well as the declaration of war was certainly significant, but perhaps rapid and successful development of safe and effective the furious diplomats chose to downplay its role? COVID-19 vaccines being distributed today. Trinity Regardless, a tenuous peace followed. Finally, on marked the dawn of modern “big science.” James September 2, the war officially came to an end aboard the Kunetka, who chronicled the relationship between USS Missouri in Tokyo Bay with General Douglas General Groves and J. Robert Oppenheimer in his book MacArthur, the Supreme Commander for the Allied The General and the Genius, explains, “Trinity created a Forces and Military Governor of Japan, presiding over the model for planning and executing future large-scale ceremony. It was the final act of a conflict that killed scientific and technological endeavors. Make no mistake, approximately 60,000,000 people worldwide.151 there is a road that runs from Trinity to Tranquility Base.”156 VII. The Myth, The Legend, The Legacy The nuclear age has witnessed extraordinary Three days after Trinity, future Nobel laureate Edwin achievements in the field of nuclear medicine. Likewise, McMillan wrote, “I am sure that all who witnessed this as the world struggles to cope with the challenges test went away with a profound feeling that they had seen presented by a changing climate, nuclear power offers a one of the great events of history.”152 There can be no clean, efficient, reliable, and still largely untapped doubt Trinity represented a transformative moment in potential solution. For instance, in 2019 nuclear power time. The test, for instance, is arguably the single-most- only accounted for 20% of all electricity generated by the significant individual scientific experiment ever United States.157 Dr. Peter Lyons, former assistant conducted. Papers in this issue illuminate the extent to secretary for nuclear energy at the Department of Energy, which the Manhattan Project was a team effort involving noted, “Many studies show that intermittent clean the US, Britain (Moore153), and Canada (Andrews et renewables need clean baseload power to achieve a

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Figure 5. Brigadier General David Trybula, commander of the White Sands Missile Range, offers remarks at ground zero as the dawn breaks on Trinity’s 75th anniversary. reliable and stable clean grid, and several labs and utilities not feasibility. Trinity revealed that a nation with are now working to demonstrate how baseload nuclear sufficient resources and persistence could develop a power can work with intermittent renewables.” Lyons weapon.”159 Oppenheimer recognized the danger explains that the promise of this technology, which is presented by this new reality. When he accepted the deeply rooted in the Manhattan Project, continues to Army-Navy “E” Award for excellence in October 1945, evolve: “New advances in nuclear power, like passive he called for nations to join together in the pursuit of safety, small modular reactors, and advanced non-light peace: “The people of this world must unite or they will water reactors, will assure a bright future for nuclear perish. This war that has ravaged so much of the earth, power.”158 has written these words. The atomic bomb has spelled Yet, Trinity was not merely a science experiment—it them out for all men to understand.”160 But thousands of was a weapons test. Nuclear weapons played a role in nuclear weapons remain in existence today. During the ending history’s deadliest war—an important part of Cold War, scientists at Los Alamos designed five of the Trinity’s legacy. There have only been two nuclear strikes seven nuclear weapons types currently maintained by the in history, and the peace those missions played a part in United States. These designs account for approximately securing cannot be separated from the immense, almost 90% of the US nuclear deterrent. unimaginable suffering they inflicted. Neither can these Although Trinity does not represent the birth of nuclear missions be separated from arguably the greatest threat of deterrence, perhaps it marks the conception of the idea. our age—nuclear proliferation. The moment Little Boy There has not been another war fought directly between detonated over Hiroshima, perhaps the greatest nuclear the great, global powers since the end of World War II. secret of them all was revealed. Thom Mason, current Most would likely agree nuclear weapons have played at director of Los Alamos National Laboratory, explains, “It least some part in keeping the peace at that lofty level. But has been said that the most significant nuclear weapons Oppenheimer’s successor, Norris Bradbury, looked secret was that they work. While there are many elements forward to the day nuclear weapons would no longer be of design that are secret, they really relate to optimization needed: “In contrast with almost every other field of

15 Submitted to ANS/NT (2021), LA-UR-21-21007 human endeavor . . . the atomic bomb business seeks to blast is barely discernable, though from a distance the scar put itself out of business,” continuing, “Our one objective on the desert floor can still be clearly seen. After the war, at Los Alamos has always been that bombs never get the polar caps of Jumbo were ripped off by several 500- used, that the United States was always ahead both in pound bombs under still-murky circumstances. technology and a willingness to discuss the abandonment Ironically, this once abandoned sentinel of despair now of nuclear warfare.”161 Bradbury’s successor, Harold greets visitors to ground zero; it is one the few original Agnew, witnessed the world’s first controlled nuclear objects from the test that has survived. chain reaction as one of Fermi’s students at the University As a member of the White Sands Public Affairs Office, of Chicago; he later filmed the attack on Hiroshima from Jim Eckles has spent more time at ground zero than high above the devastation. During the Laboratory’s 50th anyone else. He has met visitors from across the globe anniversary celebration, Agnew asked an audience at Los and answered thousands of questions over the decades; Alamos if there was a more peaceful use for nuclear perhaps there is no one more ideally suited to assess energy than “bringing about a quick end to a frightful war; Trinity’s legacy. What does the nuclear age’s birthplace providing a realistic deterrent during the cold war and mean to Eckles? “Trinity Site means public open houses through this deterrent, antsy as it may have been, bringing and making sure there are enough portable toilets for three about the demise of the political system of the Evil thousand people, watching long lines of cars waiting to Empire and its slave states and offering all of Europe and park, hoping the shuttle bus system holds up, helping the world a chance for democracy and an open society.”162 people understand fission and radiation, and wondering Though the existence of nuclear weapons has introduced where they all come from year after year after year.”163 opportunities for terrible accidents and ruinous conflicts, As for the test that unfolded there 75 years ago, Eckles they have also provided some measure of stability to a continues, “As a historian Trinity Site is a symbol of what perennially unstable world. Trinity embodies this ingenious and resourceful human beings can accomplish paradox: the hope of peace through the threat of danger, when they work as a team. They changed the world in the and the presence of otherworldly beauty in unimaginable blink of an eye. Now it is up to other clever humans to devastation. deal with the consequences.” And perhaps this is the most Over the past 75 years, the landscape at ground zero has intriguing aspect of Trinity—its story is not yet fully changed considerably. The sea of trinitite is now gone; revealed. only tiny fragments of the atomic mineral remain for curious visitors to rediscover—but not keep—during Acknowledgements biannual open house events hosted by White Sands. A The author wishes to thank Los Alamos National small area of largely untouched trinitite has been Laboratory (LANL) editor Craig Carmer, LANL archivist protected by an enclosure for many years, but the desert Daniel Alcazar, historians Jim Eckles and James sand has gradually invaded the structure and obscured its Kunetka, National Cancer Institute researcher Steven precious contents. The exposed rebar of the tower Simon, LANL scientist Thomas Kunkle, LANL historian footings that survived the blast has been cut down to the Ellen McGehee, and Los Alamos affiliate Thomas ground. In the tower’s wake, for many years there has Chadwick for providing ongoing assistance in the been an obelisk bearing a plaque that reads, “TRINITY preparation of this paper. The author is also indebted to SITE: Where the World’s First Nuclear Device was the staff of the LANL Classification Office and several Exploded on July 16, 1945.” A chain-link fence keeps additional colleagues who made important contributions visitors from straying into the wider expanse of the to this paper. missile range; the site remains a place of carefully controlled violence. The shallow crater created by the References and Notes

1 The end of the plutonium gun effort is covered in L. HODDESON et 6 J. HUTCHINSON et al., “Criticality Experiments with Fast 25 and 49 al., Critical Assembly: A Technical History of Los Alamos During the Metal and Hydride Systems During the Manhattan Project,” Nucl. Oppenheimer Years, 1943–1945 (Cambridge: Cambridge University Technol., this issue (2021). Press, 1997), 236–44. 7 R. KIMPLAND et al., “Critical Assemblies: Dragon Burst Assembly 2 “Administrative Board Minutes for July 20, 1944,” Los Alamos & Solution Assemblies,” Nucl. Technol., this issue (2021). National Laboratory (LANL), National Security Research Center 8 J. R. OPPENHEIMER to R.F. Bacher, “Organization of Gadget (NSRC), collection A-1983-013, box 1, folder 52, p. 5. Division,” LANL, NSRC, collection A-1984-019, box 25, folder 13 3 D. BOROVINA and E. BROWN, “The Trinity High Explosive (August 14, 1944 ); J. R. OPPENHEIMER to G. B. KISTIAKOWSKI, Implosion System: The Foundation for Precision Explosive “Organization of Explosives Division,” LANL, NSRC, box 35, folder Applications,” Nucl. Technol., this issue (2021). 11 (August 14, 1944). 4 R. MOORE, “Woolwich, Bruceton, Los Alamos: Munroe Jets and the 9 N. R. MORGAN and B. J. ARCHER, “On the Origins of Lagrangian Trinity Gadget,” Nucl. Technol., this issue (2021). Hydrodynamic Methods,” Nucl. Technol., this issue (2021). 5 M. B. CHADWICK, “Nuclear Science for the Manhattan Project & 10 A. SOOD et al., “Neutronics Calculation Advances at Los Alamos: Comparison to Today’s ENDF Data,” Nucl. Technol., this issue (2021). Manhattan Project to Monte Carlo,” Nucl. Technol., this issue (2021).

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37 K. T. BAINBRIDGE, “A Foul and Awesome Display,” Bulletin of the 11 Atomic Scientists (May 1975), 43. J. LESTONE, M. D. ROSEN, and P. J. ADSLEY, “Comparison 38 J. MORGAN, “The Origins of Blast Loaded Vessels,” Nucl. Technol., Between Historic Nuclear Explosion Yield Formula,” Nucl. Technol., this issue (2021). this issue (2021). 39 12 Commander N. E. BRADBURY to Personnel Concerned, “TR Hot N. LEWIS, “Trinity by the Numbers: The Computing Effort that Made Run,” LANL, NSRC, collection A-1984-019, box 16, folder 6 (July 9, Trinity Possible,” Nucl. Technol., this issue (2021). 13 1945) 1. The Creutz device’s HE assembly was prepared at Pajarito Site; B. J. ARCHER, “The Los Alamos Computing Facility During the the Trinity device’s at V Site. Both areas are now Manhattan Project Manhattan Project,” Nucl. Technol., this issue (2021). 14 National Historical Park sites deep within LANL. N. F. RAMSEY to J. R. OPPENHEIMER, W. S. PARSONS and N. 40 R. RHODES, The Making of the Atomic Bomb (New York: Simon and BRADBURY, “Unsatisfactory Features of Weapons Program,” LANL, Schuster, 1986), 656–7. NSRC, collection A-1984-019, box 64, folder 25, (June 23, 1945). 41 15 U.S. Department of Energy Office of Health, Safety and Security J. C. MARTZ, F. J. FREIBERT, and D. L. CLARK, “The Taming of Office of Classification, “Restricted Data Declassification Decisions Plutonium: Plutonium Metallurgy and the Manhattan Project,” Nucl. 1946 to the Present, RDD-8” (January 1, 2002), 77. Technol., this issue (2021). 42 16 R. RHODES, 659. S. CROCKETT and F. FREIBERT, “Equation of State: Manhattan 43 G. B. KISTIAKOWSKI, “Trinity—A Reminiscence,” The Bulletin of Project Developments and Beyond,” Nucl. Technol., this issue (2021). 17 the Atomic Scientists (June 1980), 20. T. A. CHADWICK and M. B. CHADWICK, “Who Invented the 44 L. HODDESON et al., 367–9. Trinity Nuclear Test’s Christy Gadget? Patents and Evidence from the 45 Classified film footage of the Trinity device’s assembly, LANL, Archives,” Nucl. Technol., this issue (2021). 18 NSRC. This configuration was referred to as the “Trap Door” design. K. T. BAINBRIDGE, “Trinity,” LANL report, LA-6300-H (May 46 H. D. NOYES to J. Robert Oppenheimer, LANL NSRC, collection A- 1976), 1. This is the unclassified version of the test director’s report; the 1984-019, box 13, folder 11 (March 11, 1943). Noyes, an assistant trust classified version is LA-1012 (1945). 19 officer with the American Trust Company, was writing to Oppenheimer R. OPPENHEIMER to General Leslie R. Groves, LANL, NSRC, regarding relatively minor personal business matters. On the back of the reference copy available, VFA-4310 (October 20, 1962). letter, Oppenheimer made a list of questions to be explored at the famous Oppenheimer’s origin story for the name Trinity has now entered into Los Alamos Primer Conference of April 1943. high culture with John Adam’s opera Dr. Atomic, which has been 47 R. RHODES, 656. performed in San Francisco, New York, and recently Santa Fe. The 48 G. B. KISTIAKOWSKI, 21. opera includes an extended aria of Oppenheimer singing Donne’s 49 K. T. BAINBRIDGE, “Trinity,” 5. “Batter my heart . . .” 50 20 L. HORGAN, “Bethe, Teller, Trinity and the End of Earth: A leader K. T. BAINBRIDGE reports that the search began in March of the Manhattan Project recalls a discussion of whether the Trinity test (“Trinity,” 1). 21 would ignite Earth's atmosphere and destroy the planet,” Scientific K. T. BAINBRIDGE to Major Peer De Silva, June 22, 1944 (NSRC American (August 4, 2015). This is an interview with Bethe. collection A-1984-019, box 43, folder 27). 51 22 Now It Can Be Told, 296–7. L. R. GROVES, Now It Can Be Told (New York: Harper & Row, 52 General Groves confirms this concern in L. R. GROVES, “Some 1962), 289. Groves further explains, “His curiosity and insatiable desire Recollections of July 16, 1945,” The Bulletin of the Atomic Scientists to have his own way in every detail would have caused difficulties and (June 1970), 26. we already had too many.” 53 23 RDD-8, 77. K. T. BAINBRIDGE, “Trinity,” 3. Three other sites were considered 54 N. E. BRADBURY “TR Hot Run,” 4. in New Mexico (the Tularosa Valley, an area south of Grants, and an 55 K. T. BAINBRIDGE, “A Foul and Awesome display,” 45. area north of Grants), as well as an area controlled by the military near 56 As quoted in J. KUNETKA, The General and the Genius: Groves and Rice, California. 24 Oppenheimer, the Unlikely Partnership that Built the Atom Bomb F. M. SZASZ, The Day the Sun Rose Twice (Albuquerque: University (Washington, DC: Regnery History, 2015), 312. of New Mexico Press, 1985), 32–3. 57 25 L. R. GROVES, “Some Recollections,” 24. These were Theodore “Ted” Hall, Klaus Fuchs, David Greenglass, 58 K. T. BAINBRIDGE, “A Foul and Awesome Display,” 45. and Oscar Seborer. 59 26 Ibid., 46. General L. R. GROVES to Chief of Staff, LANL, NSRC, reference 60 R. RHODES, 668. copy available as VFA-4324 (July 30, 1945). Groves was reporting to 61 J. ECKLES, Trinity (Las Cruces: Fiddlebike Partnership, no date), 49. General George C. Marshall, chief of staff of the U.S. Army, on what to 62 H. C. BUSE [sic], “Directions for Personnel at Base Camp at Time of expect for the upcoming combat strikes. 27 Shot,” LANL, NSRC, collection A-2020-019 (July 15, 1945). Though T. O. PALMER, “Evacuation Detachment,” LANL, NSRC, collection misspelled on the directions, the author is Howard C. Bush, the camp’s A-1984-019, box 8, folder 1 (no date). Palmer served as the detachment commander. Like almost all instructions originating from the Health commander. 28 Group, using a welder’s filter was merely a suggestion: “they will look B. C. HACKER, The Dragon’s Tail: Radiation Safety in the at the flash only on their own responsibility,” from “Abstract of Manhattan Project, 1942–1946 (Berkeley: University of California Conferences on Medical Hazards Held Before Trinity Shot” (NSRC Press, 1987), 80–1. 29 collection A-2020-019). L. HODDESON et al., 362. 63 30 F. M. SZASZ, 82, and R. RHODES, 669. L. H. HEMPELMANN to file, “Hazards of the 100 Ton Shot at 64 R. RHODES, 669, and L. LANSING, Day of Trinity (New York: Trinity,” LANL, NSRC, collection A-2020-019 (May 18, 1946). This Atheneum, 1965), 225. semiprocessed collection does not include folder numbers at the time of 65 J. KUNETKA, 317. Szasz reports Tchaikovsky’s Nutcracker Suite this writing. 31 could be heard during the final seconds of the countdown (p. 82). J. R. OPPENHEIMER to General Leslie R. Groves, LANL, NSRC, 66 R. RHODES, 669–70. collection A-1984-019, box 16, folder 4 (June 27, 1945). 67 32 J. KUNETKA, 318. PALMER, “Evacuation Detachment.” 68 33 K. T. BAINBRIDGE, “Trinity,” 31. The precise moment of the Historic American Engineering Record, Trinity Site (HAER No. NM- detonation is unknown, but Bainbridge writes: “The best figure is July 1A), 30. 34 16, 1945, 5:29:15 a.m. MWT plus 20 s minus 5 s error spread.” B. RISTVET to Alan B. Carr, personal communication (December 69 W. L. LAURENCE, “Eyewitness Account of Bomb Test,” New York 13, 2020). Both Ristvet and the author knew Ben Benjamin well. 35 Times (September 26, 1945). Lithuania was part of the Russian Empire K. T. BAINBRIDGE, “Trinity,” 5. Postwar test towers were at the time of Laurence’s birth. constructed to keep fireballs from contacting the surface, but there is currently no known evidence this was considered for Trinity. 36 Ibid, 4.

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Penney (later knighted). Moon’s measurements also contributed to the 70 map. Trinity to Trinity: Director’s Round Table Discussion, video 98 J. H. ALLEN to L. H. Hempelmann, “Visitors to TR,” LANL, NSRC, recording, LANL (July 16, 2015). 71 collection A-2020-019 (August 2, 1945). R. RHODES, 673. 99 72 L. H. HEMPELMANN to files, “Visit of Reporters to Trinity,” S. K. HANSON and W. J. OLDHAM, “Weapons Radiochemistry: LANL, NSRC, collection A-2020-019 (September 29, 1945). Trinity and Beyond,” Nucl. Technol., this issue (2021). 100 73 H. C. BUSH to James Nolan, “Crater Area Register,” LANL, NSRC, H. D. SELBY et al., “A New Yield Assessment for the Trinity Nuclear collection A-2020-019 (January 18, 1946). Test, 75 Years Later,” Nucl. Technol., this issue (2021). 101 L. M. GOLLWITZER to Paul Aebersold, “Removal of Soil Samples 74 K. T. BAINBRIDGE, “Trinity,” 12. 75 From Trinity For the University of New Mexico,” LANL, NSRC, N. EBY et al., “Trinitite—The Atomic Rock,” Geology Today, vol. collection A-2020-019 (November 1, 1945). 26, no. 5 (September–October 2010), 181. 102 76 L. H. HEMPELMANN to Howard C. Bush, “Safety Instructions Consider J. O. HIRSCHFELDER and J. MAGEE to K. T. Bainbridge, Concerning Military Personnel and Visitors In and Around Crater “Improbability of Danger from Active Material Falling From Cloud,” Region,” LANL, NSRC, collection A-2020-019, (October 22, 1945). LANL, NSRC, collection A-2020-019 (July 6, 1945). 103 77 H.O. WHIPPLE to Mr. Bradbury, “Access to Trinity Crater,” LANL, D. J. MERCER et al., “Gamma and Decay Energy Spectroscopy NSRC, collection A-2020-019 (December 3, 1945). Bradbury then Measurements of Trinitite,” Nucl. Technol., this issue (2021). 78 served as the laboratory director, a position he held until 1970. E. FERMI, “My Observations During the Explosion at Trinity on July 104 L. H. HEMPELMANN, “Final Organization for Trinity Test #2 as of 6, 1945,” LANL, NSRC, collection A-1984-019, box 16, folder 5. 79 July 15, 1945” LANL, NSRC, collection A-2020-019. J. I. KATZ, “Fermi at Trinity,” Nucl. Technol., this issue (2021). 105 80 “Final Plans for Monitoring and Evacuation N.W. and N.W. [sic] R. S. BATY and S. D. RAMSEY, “On the Symmetry of Blast Waves,” Regions as of 14 July 1945” LANL, NSRC, collection A-2020-019. The Nucl. Technol., this issue (2021). 81 document appears to be authored by Hoffman. Hot Springs is now Oppenheimer shared these thoughts on the 1965 NBC documentary, named Truth or Consequences. Soil samples were also collected. The Decision to Drop the Bomb. Consider J. A. HIJIYA, “The Gita of 106 “Town Radiation Report (Film Method),” LANL, NSRC, collection J. Robert Oppenheimer,” Proceedings of the American Philosophical A-2020-019. Society, volume 144, number 2 (June 2000). Hijiya confirms 107 S. L. SIMON et al., “Estimated Radiation Doses Received by New Oppenheimer mistakenly referred to Vishnu; the quote actually comes Mexico Residents from the 1945 Trinity Nuclear Test,” Health Physics, from Krishna. 82 119, (4), 428–477 (2020). Both quotes come from a documentary by J. ELSE, The Day After 108 L. H. HEMPELMANN to J.G. Hoffman, “Procedure To Be Used by Trinity. Frank Oppenheimer was named chair of the committee on June Town Monitors To Provide Admissible Evidence for Future Medical 30; see K. BAINBRIDGE to all concerned, “TR Circular No. 17 – Legal Cases,” LANL, NSRC, collection A-2020-019 (July 9, 1945). Safety Committee for TR,” LANL, NSRC, collection A-2020-019 (June Earth samples were also collected for legal purposes. 30, 1945). 109 M. R. ALLEN to K.T. Bainbridge, “Search Light Report,” LANL, 83 R. RHODES, 675. 84 NSRC, collection A-2020-019 (July 17, 1945). G. B. KISTIAKOWSKI, 21. 110 85 V. WEISSKOPF et al., “Measurement of Blast, Radiation, Heat and K. JOHNSON, “To Norris Bradbury, Being LASL’s Director has Light, and Radioactivity at Trinity,” LANL, NSRC, collection A-2020- been A Quarter Century of Fun,” The Atom, vol. 7, no. 8 (September 019 (September 5, 1945). 1970), 13. 111 86 Ibid. M. BRADNER, "Trinity, July 16, 1945 5:29:45 AM," Bear Facts, vol. 112 J. L. MAGEE to Joseph Hoffman, “Radiation Measurements Made 33, no. 9 (June 1995), 4. 87 on 7-16-45. Reported 7-21-45,” LANL, NSRC, collection A-2020-019, As quoted by Ben Benjamin in Project Trinity: An Enlisted Man’s 2. Perspective, Los Alamos National Laboratory Heritage Series Lecture, 113 W. MCELWREATH, “Memorandum to the Officer in Charge,” LANL, NSRC, video recording (July 12, 2005). 88 LANL, NSRC, collection A-2020-019 (July 16, 1945), 3. R. RHODES, 675. 114 No author, “Events in Camp Immediately Following Shot—July 16, 89 Ibid., 677. 90 1945 (Summarized from Col. Warren’s and Hempelmann’s Personal G. L. HARRISON to Henry L. Stimson, “Number WAR 32887,” Notes),” LANL, NSRC, collection A-2020-019, 1–2. LANL, NSRC, VFA-4320 (July 16, 1945). 115 91 P. C. AEBERSOLD to L.H. Hempelmann, “Protection and Associated Press, “Windows at Gallup, 235 Miles Away Rattle; No Monitoring on TR Site for Shot No. 2 Preliminary Report,” LANL, Loss of Lives,” Albuquerque Journal (July 17, 1945). 92 NSRC, collection A-2020-019 (July 20, 1945), 3. J. G. HOFFMAN, “Nuclear Explosion 16 July 1945: Health Physics 116 No author, “Las Vegas Trip,” LANL, NSRC collection A-2020-019 Report on Radioactive Contamination Throughout New Mexico (July 18, 1945). Following the Nuclear Explosion,” LANL, LA-626 (February 20, 117 A. BOUVILLE et al., “The Methodology Used to Assess Doses from 1947), 18. 93 the First Nuclear Weapons Test (Trinity) to the Populations of New Consider “Electronic Code Federal Regulations, Title 10 (Energy),” Mexico,” Health Physics, October 2020, Volume 119, Number 4 Chapter III, Part 835. This law sets the limit at 5 rem/year, which is (October 2020), 404. approximately 5 R. 118 94 S. L. SIMON et al., “Cancer Risk Projection Study for the Trinity K. T. BAINBRIDGE, “Trinity,” 31. The plan was originally published Nuclear Test—Community Summary,” National Cancer Institute, as a July 20 memo “Hazards of TR #2,” LANL, NSRC, collection A- Division of Cancer Epidemiology & Genetics; 2020-019. 95 https://dceg.cancer.gov/research/how-we-study/exposure- “Abstract of Conferences on Medical Hazards Held Before Trinity assessment/community-summary (accessed January 13, 2021). This Shot,” 3. 96 Congressionally mandated study took six years to reach publication. H. L. ANDERSON to K.T. Bainbridge, “The 100-Ton Shot 119 A video summary of the NCI study can be found at S. L. SIMON et Preparations—Addition No. 7 to Project TR Circular,” LANL, NSRC, al., “Study to Estimate Radiation Doses and Cancer Risks from collection A-2020-019 (April 19, 1945), 3. 97 Exposure to Fallout from the Trinity Test,” YouTube; No author, “To People Entering the Area After the Shot,” LANL, https://www.youtube.com/watch?v=QvVpq3q9KYc&feature=youtu.be NSRC, collection A-2020-019. The original document includes the (accessed February 11, 2021). signatures of several individuals mentioned in this paper: Kenneth 120 No author, “Summary of examples of town monitoring: gamma Bainbridge, Joseph McKibben, Frank Oppenheimer, and Ben Benjamin. roentgen doses,” LANL, NSRC, collection A-2020-019, Table IVa. Future Nobel laureate Frederick Reines also signed it, as did several 121 “Events in Camp Immediately Following Shot,” 3. British scientists tasked with measuring the test: Derrick Littler, Herold Sheard, James Hughes, Philip Moon, William Marley, and William

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140 Consider J. HERSEY, “A Reporter At Large: Hiroshima,” The New 122 Yorker (August 31, 1946). L. H. HEMPELMANN, “Itinerary of Trip made by Colonel Warren, 141 A. W. OUGHTERSON et al., Medical Effects of Atomic Bombs: The Captain Whipple and L.H. Hempelmann on 12 August 1945,” LANL, Report of the Joint Commission for the Investigation of Effects of the NSRC, collection A-2020-019 (August 17, 1945), 3. 123 Atomic Bomb in Japan, Volume 1 (Army Institute of Pathology: April L. H. HEMPELMANN, “Dosage of Radiation Received by People 19, 1951), 12, and “U.S. Naval Technical Mission to Japan, Atomic in Hot Canyon,” LANL, NSRC, collection A-2020-019. 124 Bombs, Hiroshima and Nagasaki: Article I,” Medical Effects (December L. H. HEMPELMANN to Trinity follow-up files, “Trip to Trinity to 1945), 56. The number 30,769 does not include Imperial Navy Purchase Cattle Alledgedly [sic] Damaged by the Atomic Bomb,” personnel. LANL, NSRC, collection A-2020-019 (December 9, 1945), 2–3. 142 125 L. HODDESON et al., Critical Assembly, 396–7. C. D. BLACKWELL and G. J. LITTLEJOHN to Dr. Beller, 143 A. W. OUGHTERSON et al., 12. “Monitoring Trinity, etc.,” LANL, NSRC, collection A-2020-019 (June 144 L. ALVAREZ, P. MORRISON and R. SERBER to Ryokichi Sagane, 19, 1947), 1–2. 126 LANL, NSRC, reference copy available, VFA-4322 (August 9, 1945). Dr. L. H. HEMPELMANN to files, “Trip to Ranches of Ted Coker 145 “Memorandum to the Chief of Staff,” 2. and Mr. Raitliff [sic] on Sunday 11, November, 1945,” LANL, NSRC, 146 L. R. GROVES to Chief of Staff, LANL, NSRC, VFA-4321 (August collection A-2020-019 (November 14, 1945), 2. 127 10, 1945). L. H. HEMPELMANN, “Transfer of Alamogordo Cattle,” LANL, 147 General HULL and Colonel SEAMAN [sic], telephone conversation NSRC, collection A-2020-019 (June 7, 1948). 128 transcript, LANL, NSRC, reference copy available, VFA-4323 (August “Trip to Trinity,” 1. In “Transfer of the Alamogordo Cattle,” 13, 1945). “Seaman” should be spelled Seeman. Hempelmann states 17 cows were sent to Los Alamos. 148 129 The Allies did not guarantee the emperor would retain his throne. On L. H. HEMPELMANN to Trinity files, “Estimate of dose of beta August 11, Secretary of State James F. Byrnes conveyed the following radiation received by cattle,” LANL, NSRC, collection A-2020-019 message to the Japanese government: “From the moment of surrender (February 10, 1946). This is one of the relatively few records from the the authority of the Emperor and the Japanese Government to rule the time that clearly delineates between different types of radiation. state shall be subject to the Supreme Commander of the Allied powers 130 “Transfer of the Alamogordo Cattle.” 131 who will take such steps as he deems proper to effectuate the surrender T. L. SHIPMAN to Elmo Morgan, “Cattle,” LANL, NSRC, terms,” further adding, “The ultimate form of government of Japan shall, collection A-2020-019 (August 19, 1950). 132 in accordance with the Potsdam Declaration, be established by the freely Consider J. H. WEBB, “The Fogging of Photographic Film by expressed will of the Japanese people.” The fragile peace that ensued Radioactive Contaminants in Cardboard Packaging Materials,” Physical was based on this somewhat ambiguous language. See Butow Review, vol. 76, no. 3 (August 1, 1949). 133 appendixes. No author, “Comments on the Administration of Town Monitoring,” 149 The Imperial Rescript of August 14, 1945, Butow appendixes. LANL, NSRC, collection A-2020-019 (no date). 150 W. J. DONOVAN to Harry S Truman, LANL, NSRC, reference copy 134 As quoted in F. M. SZASZ, 144. 135 available, VFA-4325 (August 14, 1945). There was a spike in infant mortality in New Mexico following the 151 This estimate comes from The National World War II Museum. test, but the possible connection between this spike and Trinity remains 152 E. M. MCMILLAN, “Impressions of Trinity Test,” LANL, NSRC, contentious. For more information, consider K. M. TUCKER and R. collection A-1984-019, box 50, folder 32 (July 19, 1945). ALVAREZ, “Trinity: The Most Significant Hazard of the Entire 153 R. MOORE, “Peierls’s 1945 Paper ‘Outline of the Development of Manhattan Project,” Bulletin of the Atomic Scientists (July 15, 2019) and the British Tube Alloy Project,’” Nucl. Technol., this issue (2021). J. D. BOICE, JR., “The Likelihood of Adverse Pregnancy Outcomes 154 S. A. ANDREWS, M. T. ANDREWS, and T. E. MASON, “Canadian and Genetic Disease (Transgenerational Effects) from Exposure to Contributions to the Manhattan Project and Early Nuclear Research,” Radioactive Fallout from the 1945 Trinity Atomic Bomb Test,” Health Nucl. Technol., this issue (2021). Physics (October 2020). Boice’s contribution to the peer-reviewed NCI 155 As quoted in, “Trinity Site Commemorates 75th Anniversary,” study discounts adverse pregnancy outcomes and genetic diseases Alamogordo Daily News (July 17, 2020). (transgenerational and heritable effects) related to population exposure 156 Personal communication with the author (September 24, 2020). to fallout. 157 136 United States Energy Information Administration, “Nuclear K. BAINBRIDGE to all concerned, “Space Assignments,” LANL, Explained: U.S. Nuclear Industry,” (April 15, 2020). NSRC, collection A-2020-019 (July 2, 1945), 4. Though it is currently 158 Personal communication with the author (January 20, 2021). unknown if Seborer communicated the success of the test back to the 159 Personal communication with the author (January 6, 2021) Soviet Union, his presence in the bunker demonstrates how deeply 160 J. R. OPPENHEIMER, “Acceptance Speech, Army-Navy Stalin’s spies infiltrated the Manhattan Project. 137 ‘Excellence’ Award,” November 16, 1945 [sic], Los Alamos Science, As quoted in H. FEIS, “The Secret that Travelled to Potsdam,” Winter/Spring 1983, 25. The speech was given October 16, 1945, in Los Foreign Affairs (January 1960), 314. The quote comes from Truman’s Alamos. diary; Feis provides additional perspectives on this memorable 161 As quoted in The First 25 Years, a Los Alamos Scientific Laboratory exchange. 138 documentary. The Potsdam Proclamation, July 26, 1945. This document, as well 162 “Talk by Harold M. Agnew,” LANL, NSRC, VFA-3626, transcript, as copies of other important diplomatic records, are included in the (April 12, 1993), 8. appendixes of R. J. C. BUTOW, Japan’s Decision to Surrender 163 Personal communication with the author (January 14, 2021). (Stanford: Stanford University Press, 1954). 139 L. HODDESON et al., Critical Assembly, 392.

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